title: Case-control analysis on metformin and cancer of the esophagus.
abstract: OBJECTIVE
  Metformin use has been associated with decreased cancer risks, though data on esophageal cancer are scarce. We explored the relation between use of metformin or other anti-diabetic drugs and the risk of esophageal cancer.
  
  
  METHODS
  We conducted a case-control analysis in the UK-based general practice research database (GPRD, now clinical practice research datalink, CPRD). Cases were individuals with an incident diagnosis of esophageal cancer between 1994 and 2010 at age 40-89 years. Ten controls per case were matched on age, sex, calendar time, general practice, and number of years of active history in the GPRD prior to the index date. Various potential confounders including diabetes mellitus, gastro-esophageal reflux, and use of proton-pump inhibitors were evaluated in univariate models, and the final results were adjusted for BMI and smoking. Results are presented as odds ratios (ORs) with 95 % confidence intervals (CI).
  
  
  RESULTS
  Long-term use (≥30 prescriptions) of metformin was not associated with a materially altered risk of esophageal cancer (adj. OR 1.23, 95 % CI 0.92-1.65), nor was long-term use of sulfonylureas (adj. OR 0.93, 95 % CI 0.70-1.23), insulin (adj. OR 0.87, 95 % CI 0.60-1.25), or of thiazolidinediones (adj. OR 0.71, 95 % CI 0.37-1.36).
  
  
  CONCLUSIONS
  In our population-based study, use of metformin was not associated with an altered risk of esophageal cancer.
authors.affiliation: Basel Pharmacoepidemiology Unit, Division of Clinical Pharmacy and Epidemiology, Department of Pharmaceutical Sciences, Basel University Hospital, University of Basel, Spitalstrasse 26, 4031, Basel, Switzerland.
authors.forename: Claudia
authors.initials: C
authors.lastname: Becker
authors.forename: Christoph R
authors.initials: CR
authors.lastname: Meier
authors.forename: Susan S
authors.initials: SS
authors.lastname: Jick
authors.forename: Michael
authors.initials: M
authors.lastname: Bodmer
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D004938:Esophageal Neoplasms / Q000453:epidemiology* / Q000517:prevention & control; D006801:Humans; D007004:Hypoglycemic Agents / Q000008:administration & dosage*; D016015:Logistic Models; D008687:Metformin / Q000008:administration & dosage*; D008875:Middle Aged; D012307:Risk Factors; D006113:United Kingdom / Q000453:epidemiology
chemical_list: D007004:Hypoglycemic Agents; D008687:Metformin